JPH10158966A - Bulky nonwoven fabric and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonwoven fabric having many thickly formed wrinkle-like projections on the surface and good surface smoothness and rich in bulkiness and elasticity. SOLUTION: This nonwoven fabric comprises the first fiber layer containing thermally shrunk bribers and the second fiber layer of layers containing non- shrinkable fibers and laminated to one or two surfaces of the first fiber layer, and has a METSUKE of >=200g/m<2> . Therein, both the fiber layers are integrally interlaced with each other by a needle punching method. Many wrinkle-like projections are thickly formed on the second fiber layer, and the apparent valley-mountain ratio of the projections and the depressions formed by the formation of the projections on the surface of the nonwoven fabric is >=0.60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulky and elastic nonwoven fabric having a large number of wrinkle-like convex portions formed on the surface thereof and having surface smoothness, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, two or more fiber layers having different heat shrinkage rates are laminated, and one fiber layer is thermally shrunk to form a wrinkle-like or pile-like projection on the other fiber layer. Various bulky nonwoven fabrics have been proposed and put to practical use. For example, Japanese Unexamined Patent Publication (Kokai) No. 53-6683 discloses a pile woven fabric characterized in that after a high-pressure columnar flow is jetted onto a laminate in which a low-shrink fiber web is superimposed on a high-shrink fiber web, a shrink treatment is performed. A method for producing a nonwoven is described. Japanese Unexamined Patent Publication (Kokai) No. 55-98951 proposes a relief-like nonwoven fabric obtained by stacking a high shrinkage nonwoven fabric and a low shrinkage nonwoven fabric, performing needling, and then heat-treating. Further, JP-A-61-132666 discloses a bulky property in which a shrinkable bottom nonwoven fabric made of a specific polyester long fiber and a surface nonwoven fabric are entangled and a loop is formed in the surface nonwoven fabric between the entangled portions. A nonwoven is described.

[0003]

However, the above-mentioned bulky nonwoven fabric has the following problems. For example,
As described in JP-A-53-6683, when a laminate of a high-shrinkable fiber web and a low-shrinkable fiber web is integrated by a high-pressure columnar water stream, the water pressure of the water stream and the pitch of the water jet nozzle are varied. Pile size easily,
Although the number can be adjusted, it becomes difficult to adjust the size and number of piles when the weight of the laminate increases. That is, if the basis weight is large, the web layers are not sufficiently entangled with each other, and a weakly entangled portion exists over a considerably wide range. Then, the entangled portion of the weakly entangled portion is easily untangled when the highly shrinkable fiber web shrinks, and the lowly shrinkable fiber layer rises in the portion. As a result, the obtained non-woven fabric is not a non-woven fabric in which pile-shaped convex portions are formed densely, but is merely a non-woven fabric in which swelling has occurred. Such a nonwoven fabric is hard to say as a nonwoven fabric having high bulkiness and elasticity because its swelling is easily collapsed and flattened by surface pressure.

[0004] Even if the water pressure is increased, the entanglement of the fibers proceeds only near the surface, so that the feeling of the obtained nonwoven fabric is hardened and the above-mentioned disadvantages cannot be solved. That is, the method of injecting and integrating the high-pressure columnar water flow is not suitable for a laminate having a large basis weight.

[0005] The nonwoven fabric described in Japanese Patent Application Laid-Open No. 55-98951 is excellent in shape-retaining property because superimposed nonwoven fabric which has been previously needled and further needled to be integrated, but many nonwoven fabrics are required for the production thereof. It requires a process and is undeniably complicated. Further, it is difficult to firmly integrate the needled nonwoven fabrics, and there is a problem that the low-shrinkage side nonwoven fabric rises and bulges at locations where the confounding is insufficient. In addition, when needling is performed from the high shrinkage nonwoven fabric, the high shrinkage fibers remain in the low shrinkage nonwoven fabric, so when heat-treated, the low shrinkage nonwoven fabric also shrinks, and the relief is formed neatly in the low shrinkage nonwoven fabric. It may not be done.

In the non-woven fabric described in JP-A-61-132666, a polyester-based long-fiber non-woven fabric is used as a shrinkable non-woven fabric, but the long-fiber non-woven fabric is essentially not easily entangled with other fibers. Therefore, even with this nonwoven fabric, it is undeniable that the above-described problem due to insufficient confounding occurs.

[0007] Further, it is considered that any of the nonwoven fabrics clearly shows the presence of loops or wrinkle-like convex portions formed on the low shrinkage layer side. In other words, it can be said that any of these is a nonwoven fabric in which unevenness on the surface is clearly recognized and lacks surface smoothness.

[0008] The present invention has been made in view of such circumstances, and a high shrinkage fiber layer and a low shrinkage fiber layer are strongly entangled, and a surface state different from that of a conventional bulky nonwoven fabric. An object of the present invention is to provide a bulky nonwoven fabric to be exhibited.

[0009]

In order to achieve the above object, the bulky nonwoven fabric of the present invention comprises a second fiber containing non-shrinkable fibers on one or both sides of a first fiber layer containing heat shrunk fibers. A nonwoven fabric having a basis weight of 200 g / m ² or more in which the layers are laminated and the two fiber layers are entangled and integrated, and a large number of wrinkle-like protrusions are densely formed on the second fiber layer, and The apparent valley to peak ratio of the unevenness of the nonwoven fabric surface caused by the formation is 0.
It is characterized by being 60 or more. Such a nonwoven fabric becomes rich in bulkiness and elasticity by the convex portions formed in the second fiber layer, and its surface is relatively smooth.

In the nonwoven fabric of the present invention, the first fiber layer contains at least 50% by weight of heat-shrinkable fibers having a maximum heat shrinkage of at least 50%, and the second fiber layer has the heat shrinkability. It is preferable to use non-shrinkable fibers that do not substantially shrink at the temperature at which the fibers shrink. By sufficiently heat shrinking the first fiber layer, it is possible to obtain a non-woven fabric having a smooth surface with convex portions formed densely.

The heat shrinkable fiber having the maximum heat shrinkage of 50% or more has a melting peak temperature (Tm ° C.) of 130 <Tm.
<145 ethylene-propylene random copolymer
Desirably, the fibers are made of a polymer containing 0% by weight or more. Since the fiber made of this polymer exhibits high heat shrinkability, it is possible to sufficiently shrink the first fiber layer by using this.

According to the method for producing a bulky nonwoven fabric of the present invention, a heat-shrinkable fiber having a maximum heat shrinkage of at least 50% is used.
A second fiber layer made of a non-shrinkable fiber that does not substantially shrink at a temperature at which the heat-shrinkable fiber shrinks on one surface of the first fiber layer containing at least 1% by weight of the first fiber layer; At a needle depth at which the number of barbs passing through the boundary surface becomes at least three, needle punching is performed from the second fiber layer side to entangle and integrate the two fiber layers, and then heat treatment is performed to shrink the heat-shrinkable fibers. By doing so, a large number of wrinkle-like convex portions are formed in the second fiber layer, and the apparent valley-to-peak ratio of unevenness on the surface of the nonwoven fabric is set to 0.60 or more. By setting the number of barbs passing through the boundary surface between the two fiber layers to 3 or more, the two fiber layers are firmly entangled with each other, and as a result, a relatively smooth nonwoven fabric having a densely formed convex portion can be obtained. It becomes possible.

In the above-mentioned manufacturing method, the area shrinkage is 5
It is desirable to perform a heat treatment so as to be 0% or more. In order to form a large number of wrinkle-shaped protrusions densely in the second fiber layer and to make the apparent valley-to-ridge ratio of the irregularities on the surface of the nonwoven fabric 0.60 or more, it is necessary to sufficiently heat-shrink the first fiber layer. There is.

In the above-mentioned production method, the first fiber layer and the second fiber layer are each preferably a fiber web composed of short fibers having a fiber length of 38 to 76 mm. The short fiber webs are liable to be strongly entangled with each other, and if the short fiber web is used as a starting material, the nonwoven fabric finally obtained has a soft touch.

In the above manufacturing method, the basis weight of the laminated state of the first fiber layer and the second fiber layer is 60 to 800 g / m2.
Desirably ² .

In the above-mentioned manufacturing method, it is desirable that the weight ratio of the first fiber layer / the second fiber layer is 3/1 to 1/1. Hereinafter, the contents of the present invention will be described.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a first fiber layer containing a heat-shrinkable fiber with a second fiber layer made of a non-shrinkable fiber which does not substantially shrink at a temperature at which the heat-shrinkable fiber thermally shrinks. The lamination is performed, and wrinkle-shaped convex portions are formed in the second fiber layer by utilizing a difference in thermal shrinkage between the two. Therefore, the first fiber layer needs to be sufficiently heat-shrinked, and the heat-shrinkable fiber contained in the first fiber layer has a maximum heat shrinkage of at least 50%.
%, And the mixing ratio is desirably 50% by weight or more. Here, the maximum heat shrinkage refers to the largest heat shrinkage of the heated fiber while maintaining the shape of the fiber. When the heat shrinkable fiber having the maximum heat shrinkage of less than 50% is used, or when the ratio of the heat shrinkable fiber is less than 50% by weight, the heat shrinkage of the first fiber layer is insufficient and the second fiber layer is insufficient. It becomes difficult to form wrinkle-like convex portions densely.

If the heat-shrinkable fibers are contained in an amount of 50% by weight or more, other fibers can be mixed in the first fiber layer. The fibers to be mixed are not particularly limited, and recycled fibers such as rayon, semi-synthetic fibers such as acetate, polyamide fibers such as nylon 6, nylon 66, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, polyethylene, polypropylene and the like. One or more selected from polyolefin fibers can be used. Of course, the first fiber layer may be composed of only heat-shrinkable fibers.

In the present invention, the maximum heat shrinkage is at least 5
As a heat-shrinkable fiber of 0%, the melting peak temperature (Tm
C) within the range of 130 <Tm <145.
It is desirable to use fibers made of a polymer containing 70% by weight or more of the propylene random copolymer. Here, the melting peak temperature is the temperature at which the DSC curve shows the highest value when the heat of fusion of the polymer is measured by a differential scanning calorimeter (DSC). If the melting peak temperature is less than 130 ° C., the polymer will exhibit rubbery elasticity, and the fiber will have poor card permeability. Conversely, if the temperature exceeds 145 ° C., the heat shrinkage of the fiber becomes about the same as ordinary polypropylene, which is not preferable. When the proportion of the ethylene-propylene random copolymer is less than 70% by weight, the maximum heat shrinkage of the obtained fiber is less than 50%, which is not preferable. As the polymer to be mixed with the ethylene-propylene random copolymer, it is desirable to use an ethylene-propylene-butene-1 terpolymer or a polyolefin-based polymer such as polypropylene.

The second fiber layer has a large number of wrinkled projections formed on the surface thereof due to the heat shrinkage of the first fiber layer. Therefore, the material constituting the second fiber layer is not particularly limited as long as it can form a fiber aggregate and does not substantially shrink at the temperature at which the heat-shrinkable fiber shrinks. For example, recycled fibers such as rayon, semi-synthetic fibers such as acetate, natural fibers such as cotton and wool, polyamide fibers such as nylon 6, nylon 66, and polyester fibers such as polyethylene terephthalate and polybutylene terephthalate. One or two or more fibers and polyolefin fibers such as polyethylene and polypropylene can be arbitrarily selected and used. The fiber shape and the like are not limited, and a core-sheath type composite fiber, a split type composite fiber, a fiber having an irregular cross section, or the like can be arbitrarily used.

For example, when the bulky nonwoven fabric finally obtained is used as a carpet or a doormat, it is preferable to use polyester fibers having a high fiber strength and a high Young's modulus. When used as a cushion material, polyester fibers and polyolefin fibers can be used. Further, the form of the nonwoven fabric can be stabilized by forming the second fiber layer by using only the heat-adhesive fibers or by mixing with other fibers, and bonding the fibers by heat.

The nonwoven fabric of the present invention is obtained by interlacing and integrating the first fiber layer and the second fiber layer by needle punch. Therefore, the form of the first fiber layer and the second fiber layer is desirably a parallel web, a cross web, a semi-random web, or a random web composed of short fibers (staple fibers) having a fiber length of 38 to 76 mm. Since a web composed of short fibers has many fiber ends and a high degree of freedom of the fibers, needle-punching of the fibers can strengthen the entanglement between the two fiber layers. Further, if needle punching is performed on the web, the manufacturing process is simplified as compared with the case where the nonwoven fabric is once needle punched, so that the nonwoven fabric can be efficiently manufactured.

It is particularly preferred that the first fiber layer is a parallel web. The fibers constituting the parallel web are arranged in almost one direction, and the direction of heat shrinkage tends to be concentrated in one direction. Therefore, the use of the fibers makes it possible to form the convex portions uniformly on the second fiber layer.

The basis weight of the state in which the first fiber layer and the second fiber layer are laminated is desirably 60 to 800 g / m ² .
Here, the state where the first fiber layer and the second fiber layer are laminated,
It means the state before needle punching. Weight is 60
If it is less than g / m ² , “uneven formation” tends to occur after needle punching. The formation unevenness directly leads to “shrinkage unevenness”, and as a result, a convex portion is not uniformly formed on the second fiber layer, which is not preferable. On the other hand, if it exceeds 800 g / m ² , the heat energy is not sufficiently transmitted to the inside of the web during the heat treatment, and the shrinkage of the first fiber layer becomes insufficient.

The weight ratio of the second fiber layer / first fiber layer is 3 /
It is desirably 1 to 1/1. If the ratio of the basis weight of the second fiber layer to the first fiber layer is large, it becomes difficult for the second fiber layer to follow the heat shrinkage of the first fiber layer, so that it is difficult to form the projection. If the ratio of the basis weight of the second fiber layer is small, the ratio of the convex portions to the total thickness of the nonwoven fabric is small, and the resulting nonwoven fabric is inferior in bulkiness and elasticity.

The first fiber layer and the second fiber layer are laminated and integrated by entanglement of the fibers. At this time, the second fiber layer may be laminated not only on one side of the first fiber layer but also on both sides.

In the present invention, it is desirable to employ a needle punch as a means for integrating the two fiber layers. According to the needle punch, the fibers can be entangled even when the basis weight of the object to be processed is large. Needle punching is desirably performed from the second fiber layer side. This is for avoiding the transfer of the heat-shrinkable fiber to the second fiber layer side as much as possible.

The number and form of the protrusions formed on the second fiber layer are determined by the needle depth and the punch density at the time of needle punching. In the present invention, it is desirable to set the needle depth such that the number of barbs of the needle passing through the boundary surface between the two fiber layers is three or more. When the number of the passing barbs is two or less, the number of fibers of the second fiber layer planted in the first fiber layer is reduced, so that the entanglement becomes insufficient and the delamination is easily caused. As a result, a swelling convex portion is easily formed in the second fiber layer, which is not preferable. As the number of barbs passing therethrough increases, the two fiber layers are strongly entangled with each other, and after heat treatment, small projections are formed densely, and the apparent valley-to-ridge ratio of the unevenness on the surface of the nonwoven fabric tends to increase.

The punch density is represented by the number of needles passing per 1 cm ^{2 of the} object. As the punch density increases, the entanglement of the fibers in each layer and the entanglement of the layers become stronger, and after heat treatment, small convex portions are formed densely.
The apparent valley ratio of the irregularities on the surface of the nonwoven fabric tends to increase.

In order to improve the surface of the nonwoven fabric, needle punching may be performed in three stages, namely, pre-punching, main punching, and finishing punching. In this case, the needle depth at the time of the main punch is set to satisfy the above-described condition. At the time of pre-punching or finishing punching, the number of barbs passing through both fiber layers may be less than three.

The needle used for the needle punch is
The needle is not particularly limited as long as it is a felting needle, and may be appropriately selected depending on the material, the basis weight, the lamination ratio, or the size, height, and the like of the convex portion to be formed. .

Next, the integrated laminate is subjected to a heat treatment to form a projection on the second fiber layer. The heat treatment is performed at a temperature at which the heat-shrinkable fibers in the first fiber layer shrink, and may be performed using a device such as a hot air penetration type processing machine or a hot air vertical blowing type processing machine. When using a hot air penetration type processing machine, the first fiber layer is more likely to contract when hot air is passed from the first fiber layer side to the second fiber layer side. The heat shrinkage of the first fiber layer is determined by the processing temperature, the processing time, and the like. In general, the higher the temperature and the longer the processing time, the greater the amount of work of thermal energy, and therefore the higher the shrinkage.

For example, when the fiber containing the above-mentioned ethylene-propylene random copolymer is used as the heat-shrinkable fiber, the heating temperature (T ° C.) is 110 <T <Tm + 30.
It is desirable to set within the range. If the temperature is lower than 110 ° C., the heat shrinkage becomes insufficient, and if it exceeds Tm + 30 ° C., the fiber is completely melted and the shrinkage stress is reduced. When processing a laminate having a basis weight of 60 to 800 g / m ² containing these fibers, the processing time may be set to several seconds to several minutes.

In the present invention, the area shrinkage of the laminate is 50%
It is desirable to perform a heat treatment so as to be as described above. More preferably, it is 60% or more, and still more preferably 70% or more. When the area shrinkage is less than 50%, the convex portions are not formed densely in the second fiber layer, and only a nonwoven fabric having a small valley-to-peak ratio of irregularities on the surface of the nonwoven fabric can be obtained.

In the laminate subjected to the heat treatment, a large number of irregular wrinkle-like protrusions are densely formed in the second fiber layer, and the apparent valley-to-valley ratio of the unevenness on the surface of the nonwoven fabric caused by the formation of the protrusions is reduced. It becomes a large nonwoven fabric. Here, the apparent valley-to-valley ratio of the unevenness is represented by a value obtained by dividing the thickness of the thickest portion (peak portion) of the nonwoven fabric by the thickness of the thinnest portion (valley portion). As shown in FIGS. 1 and 2, it can be said that the larger the value of the valley ratio, the smoother the surface of the nonwoven fabric. In the present invention, the apparent valley-to-peak ratio of the unevenness is preferably 0.60 or more.
More preferably, it is 70 to 0.95. 0.60
If less, the unevenness is clearly recognized due to the smoothness of the surface. As shown in FIG. 2, when the valley-to-valley ratio of the unevenness is small, the convex portion tends to fall down due to the surface pressure, and thus the nonwoven fabric is inferior in bulkiness and elasticity. When the number of barbs passing through both fiber layers is increased or the needle punch density is increased, a nonwoven fabric having small projections as shown in FIG. 3 can be obtained.

[0036]

The present invention will be described below with reference to examples. During the operation, the evaluation of the physical properties and the like of the nonwoven fabric was performed as follows.

(Thickness) Thickness measuring device (trade name: THICKNES
Using a S GAUGE model CR-60A (manufactured by Daiei Kagaku Seiki Seisaku-Sho, Ltd.), the measurement was performed with a load of 3 g / cm ² applied to the nonwoven fabric.

(Area Shrinkage Ratio) A square frame of 20 cm × 20 cm is placed on the surface of the nonwoven fabric before the heat treatment, and a mark corresponding to the midpoint of each side is marked. Then, after the heat treatment, the midpoints facing each other are connected with a line, and as a result of the heat shrinkage of the heat-shrinkable fiber, the area of the rectangle is calculated assuming that the square has become a rectangle in which those lines are vertical and horizontal. The area shrinkage was determined from the following equation.

[0039]

(Equation 1)

(Apparent valley-to-valley ratio of unevenness) An optical microscope photograph of the cross section of the nonwoven fabric was taken (magnification: 6 times).
The thickness of the nonwoven fabric was measured with the maximum portion as a peak and the minimum portion as a valley, and each thickness was measured to calculate (valley thickness) / (peak thickness). Three photographs were taken of one sample, and (thickness of valley) / (thickness of ridge) was calculated for each photograph, and the average value was defined as an apparent valley-to-valley ratio of unevenness.

[Production of heat-shrinkable fiber]
An ethylene-propylene random copolymer having a melt flow rate value (230 ° C.) of 15 g / 10 min was spun at a spinning temperature of 26.
It was melt spun at 0 ° C. Next, this was stretched 3.6 times at 90 ° C., and a mechanical crimp of 16 pieces / inch was given by a stuffing box while applying a fiber treatment agent.
After drying with hot air for minutes, the staple fiber was cut to obtain a staple fiber having a fineness of 2 denier and a fiber length of 51 mm. The maximum heat shrinkage of this fiber was 92% at 150 ° C. The maximum heat shrinkage was measured by bundling 50 fibers, marking them at predetermined intervals with black cotton yarn, exposing them to an atmosphere at a temperature of 150 ° C. for about 30 seconds, and measuring the marked intervals. The calculated shrinkage was defined as the maximum heat shrinkage. Melting peak temperature (melting point)
Although the measurement was performed at a higher temperature, the processing time was short, so that the fiber could be contracted while maintaining the fiber shape.

Examples 1 to 4 and Comparative Examples 1 and 2 A web prepared by a parallel card using only the above-mentioned heat-shrinkable fibers was prepared as the first fiber layer. On the other hand, as the second fiber layer, a web prepared by a parallel card using only a sheath-core type heat-adhesive conjugate fiber (denier: 2 denier, fiber length: 51 mm) having a sheath component of high-density polyethylene and a core component of polypropylene. Was prepared. Then, the second fiber layer was laminated on the upper surface of the first fiber layer so that the weight ratio of the first fiber layer and the second fiber layer in each of the examples and comparative examples was as shown in Table 1.

Next, both fiber layers were integrated from the second fiber layer side of the laminate using a punch needle (manufactured by Foster Needle Co., Ltd., needle number # 40, 9 bars). After pre-punching each with a punch density of 32 N / cm ² and two barbs passing through both fiber layers, setting the needle depth as shown in Table 1 and final punching with a punch density of 129 N / cm ² Finish punching was performed at a punch density of 97 N / cm ^{2 so} that the number of barbs passing through both fiber layers was one.

Subsequently, hot air was passed through the first fiber layer side using a hot air penetration type processing machine.
By performing the heat treatment for 2 seconds, the first fiber layer was shrunk to form wrinkle-shaped convex portions on the second fiber layer.

[Comparative Example 3] A laminate of the first fiber layer and the second fiber layer was prepared in the same manner as in the above embodiment, and
From a nozzle orifice having a pore size of 0.1mm was provided at 1mm intervals, columnar water flow pressure 30kg / cm ² was ejected from the second fiber layer side, a further columnar water flow ^{60kg / cm 2, 100kg / cm} 2 second By spraying from the fiber layer side, both fiber layers were entangled and integrated. Next, the above example was subjected to a heat treatment in the same manner to shrink the first fiber layer.

Table 1 shows the thickness, specific volume, surface shrinkage, and apparent valley-to-valley ratio of the unevenness of the nonwoven fabrics of the examples and comparative examples.

[0047]

[Table 1]

As shown in Examples 1 to 3, the needle depth was increased and the bar passing through the boundary between the first fiber layer and the second fiber layer was increased.
As the number of steps increases, a large number of wrinkles are formed densely, and the apparent valley-to-peak ratio of the unevenness increases.

Further, even if the needle depth is the same, if the ratio of the first fiber layer to the second fiber layer changes, the number of bars passing through the boundary surface between the two fiber layers also changes. In Comparative Example 1, needle punching was performed at the same needle depth as in Example 4.
Since the boundary surface between the two fiber layers is located lower than in Example 4, the number of passing barbs is two. Therefore, both fiber layers are not sufficiently entangled, and both the rate of increase in the thickness of the nonwoven fabric and the unevenness ratio are smaller than those in Example 4. This indicates that in the nonwoven fabric of Comparative Example 1, the protrusions were not formed sufficiently densely in the second fiber layer. In Comparative Example 2, the number of passing barbs was small, the basis weight of the second fiber layer was large, and the second fiber layer could not follow the heat shrinkage of the first fiber layer, so that no projection could be formed.

In Comparative Example 3, the entanglement between the first fiber layer and the second fiber layer was uneven because the energy of the water stream was not efficiently transmitted to the inside of the nonwoven fabric. Therefore, there are many bulging convex portions in the formed convex portions, and the density of the convex portions is insufficient. Therefore, the apparent valley-to-peak ratio of the unevenness on the surface of the nonwoven fabric is small.

[0051]

The bulky nonwoven fabric of the present invention has a feature that the apparent valley-to-valley ratio of the surface irregularities is large because a large number of wrinkled convex portions are densely formed on the surface thereof.
Due to this feature, the bulky nonwoven fabric of the present invention exhibits a surface state and a tactile sensation that cannot be obtained with a conventional bulky nonwoven fabric, and has excellent bulkiness and elasticity. This non-woven fabric
It is suitable for interior goods such as carpets and entrance mats, interior materials and the like. Further, since the fibers in the second fiber layer are oriented in the thickness direction due to the heat shrinkage of the first fiber layer, it can be used as a cushion material or a filter.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bulky nonwoven fabric according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an example of a nonwoven fabric having a small apparent valley ratio of irregularities on the surface of the nonwoven fabric.

FIG. 3 is a sectional view of a bulky nonwoven fabric according to another embodiment of the present invention.

Claims (8)

[Claims] A second fiber layer containing non-shrinkable fibers is laminated on one or both sides of a first fiber layer containing heat-shrinked fibers, and a basis weight of 200 g /
A m ² or more nonwoven, a second fibrous layer projecting portion of the number of wrinkle-like are formed densely in, and Taniyama ratio of apparent irregularities of surface of the nonwoven fabric caused by the formation of the convex portion is 0.60 or more A bulky nonwoven fabric characterized by the following. 2. The first fiber layer contains at least 50% by weight of heat-shrinkable fiber having a maximum heat shrinkage of at least 50%, and the second fiber layer has a temperature at which the heat-shrinkable fiber shrinks. The bulky nonwoven fabric according to claim 1, wherein the bulky nonwoven fabric is made of non-shrinkable fibers that do not substantially heat shrink. 3. The heat-shrinked fiber has a melting peak temperature (T
3. The bulky nonwoven fabric according to claim 2, wherein the fiber is a fiber comprising a polymer containing 70% by weight or more of an ethylene-propylene random copolymer having a temperature of 130 <Tm <145. 4. A non-shrinkable material that does not substantially shrink at a temperature at which the heat-shrinkable fiber shrinks on one surface of a first fiber layer containing 50% by weight or more of a heat-shrinkable fiber having a maximum heat shrinkage of at least 50%. Needle punch from the second fiber layer side at a needle depth at which the number of bars passing through the boundary surface between the first fiber layer and the second fiber layer is at least three. After the two fiber layers are entangled and integrated, heat treatment is performed to shrink the heat-shrinkable fibers, thereby forming a large number of wrinkle-like protrusions on the second fiber layer densely, and A method for producing a bulky nonwoven fabric, characterized in that an apparent valley-to-ridge ratio of unevenness is 0.60 or more. 5. The method according to claim 4, wherein the heat treatment is performed so that the area shrinkage ratio is 50% or more. 6. The method for producing a bulky nonwoven fabric according to claim 4, wherein the first fiber layer and the second fiber layer are each a fiber web composed of short fibers having a fiber length of 38 to 76 mm. 7. The method for producing a bulky nonwoven fabric according to any one of claims 4 to 6, wherein the basis weight of the laminated state of the first fiber layer and the second fiber layer is 60 to 800 g / m ² . 8. The ratio of the basis weight of the second fiber layer / first fiber layer is 3
The method for producing a bulky nonwoven fabric according to any one of claims 4 to 7, wherein the ratio is from 1/1 to 1/1.